In a computer room or Internet data center (IDC), there is a tendency that the amount of heat generated from electronic devices such as servers rapidly increases, as the electronic devices are each built in higher density. Thus, it is desired to appropriately cool the electronic devices.
Examples of a method of cooling down the electronic devices include a method of controlling air current in a room for preventing occurrence of an excessively hot part, and a method of cooling the inside of a room by air conditioning.
In order to always keep the cooling state in the room optimum by these methods, it is effective to always monitor temperature measurement points in the room. In particular, if it is possible to figure out a three-dimensional temperature distribution in the room, the cooling state in the room may be kept optimum by controlling the air conditioning or the like by use of the temperature distribution.
One of known methods of measuring such a temperature distribution is a method using an optical fiber for a temperature sensor.
However, although it is relatively easy to measure temperature of a wide area with high accuracy by the temperature measurement using an optical fiber, a method of measuring a temperature of a narrow area such as a server in a data center with high accuracy is not established yet.    Patent Document 1: Japanese Laid-open Patent Publication No. 2004-28748    Patent Document 2: Japanese Laid-open Patent Publication No. 06-109557    Non-Patent Document 1: Fujitsu Laboratories Ltd. PRESS RELEASE “Fujitsu Develops Technology Enabling Real-time Multiple-Point Temperature Measurement” Apr. 4, 2008